Low-water safety attachment



(No Model.) 2 Sheets-Sheet 1.

J. S. GRIFFITH.

LOW WATER SAFETY ATTACHMENT.

No. 341,905. Patented May 18,1886.

N. PETERS. Phnlu-Lllhugmphef. waslvingmm D. c.

(No Model.) 2 Sheets-8heet 2.

J. S. GRIFFITH.

LOW WATER SAFETY ATTAGHMENT.

No. 341,905. Patented May 18, 1886.

N. PETERS. Pnmhma m mr. Washingwn, 0.0.

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JAMES S. GRIFFITH, OF SPRINGFIELD, ILLINOIS, ASSIGNOR OF THREE- FOURTHSTO ROBERT G. SPEER, OF ST. LOUIS, MISSOURI.

LOW -WATER SAFETY ATTAC H M ENT.

SPECIFICATION forming part of Letters Patent No. 841,905, dated May 18,1886.

Application filed March 6, 1884. Serial No. 123,245.

To aZZ whom, if; may concern.-

Be it known that 1, JAMES S. GRIFFITH, a citizen of the United States,and a resident of Springfield, in the county of Sangamon and State ofIllinois, have invented certain new and useful Improvements inLow-\Vater Safety Attachments for Steam-Boilers, of which the followingis a specification,

This invention relates to that class of lowwater safety attachments tosteam-boilers in which dependence is placed upon the fusion of a body offusible metal to relieve the boiler of pressure; and my improvement hasfor its objects, first, to cause the boiler to be relieved of pressurewhen the danger-line is reached and before the crown-sheet or upperlines or tubes of the boiler are left uncovered, and thus avoid theburning out of said crown sheets or fines, as has been the case usuallywith the fusible plugs heretofore employed; second, to permit of theready closing of the blow-off mechanism after the boiler has beenrelieved of pressure; and, third, to provide a system of automaticallyoperating compound valves for relieving the boiler of pressure in a veryready and efficient manner. I attain such objeets by the constructionand arrangement of parts, illustrated in the accompanying; drawings, inwhich- Figure 1 is alongitudinal section of a hori zontal flue-boiler towhich my improvement is applied. Fig. 2 isa detail longitudinal sectionof the same; and Fig. 3 is an elevation, partly in section, illustratingmy improvements applied to a boiler of the locomotive type.

Similar letters of reference indicate like parts in the several views.

As illustrated in the drawings, my improvement consists of acontaining-tube, A, the lower end of which is closed and passes throughthe crown-sheet or one of the upper rows of fines or tubes of theboiler, so as to be exposed directly to the fire. Its upper end passesthrough the top of the boiler, preferably through a stuffing-box, A, asshown.

Within the containing-tube A is placed a body of fusible metal,preferably block-tin, in which is embedded in proper position the lowerenlarged end of the valve-holding stem or rod a. This stem or rodextends up through a (N0 model.)

loose washer at the top of the containing-tube A, and is connected tothe end of the lever B of the small relief-valve B, the arrangementbeing such that upon the water in the boiler falling below a givendanger-line, it will leave the lower end of the containingtube Aunprotected or uncovered by water, allowing the fusible metal to meltand release the valveholding rod a and permit the valve B to open,

so as to assist in relieving the boiler of pressure. This relieving ofthe boiler from pressure is further assisted by connecting theshort armI) of the valve-lever B to the short arm of the lever O of the largerelief or safety valve C, so as to cause the same to open.

In order to enable the safety apparatus, as above described, to act andrelieve the boiler of pressnre,when such danger-line is reached,

which will usually be before the upper surface of the top row of tubes,flue, or crownsheet are exposed in an uncovered condition to the actionof the fire, I form a part of the boiler that is in contact with thefire or heated products of combustion, and adjacent to and under thewater-line of the boiler, with an upwardly-projecting hollow portion, tothe crown of which is attached the lower closed end of thefusible-n1etal-containing tube A. \Vith this construction, as the waterin the boiler falls fallen sufficiently to uncover the tube or por- 5 4tion of the boiler to which. attachment is made. In cases where myimprovement is to be applied to a tubular boiler, I form suchupwardly-projecting hollow portion by forming one of the upper row oftubes, D,witl1 a raised 9 curved portion, (i, into which is screwed orotherwise secured the lower end of the fusiblemetal-containing tube A,as indicated in Figs. 1 and 2.

In cases where my improvement is to be applied to a flue-boiler in whichit is impracticable to form a bend or curve, as above set forth, in oneof the lines owing to its large diameter, or where the application ismade to the crownsheet of an internally-fired boiler, as illustrated inFig. 3, I form the upwardlyprojecting hollow portion, heretoforedescribed, by means of a dome, E, that is screwed into or otherwisesecured to one of said flues or to the crownsheet of the fire-box, asillustrated in Fig. 3.

In most cases the valve can be the ordinary safety-valve of the boiler,and can be of any of the 'usual forms of the same, either weighted, asshown, or the usual spring popvalve, as found most desirable orconvenient.

In order to render the main valve 0 capable of operation independent ofthe valve B,so as to act independently of the same for ordinarysafety-valve purposes, I make connection between the shorter arms of thevalve-levers B O by means of a compensating set-screw, c, which iscapable of adjustment so as to bring the two valves in unison to a seat.

It is preferable to form the smaller valve B with alower valve portion,b, and a disk portion, I)", which acts as a piston within thecylindrical extension B of the valve-casing, the purpose being to imparta limited positive motion to said valve and its lever,and insure anopening of the main or safety valve 0.

b are small openings in the valve-casing to 2 5 permit of the escape ofthe steam passing up through the opening of the valve B In use theseopenings may be dispensed with and the upper part of the valve-casingformed with grooves or corrugations,so as to furnish escapepassages forthe steam after the valve has raised to a certain height.

With my improvement, after the boiler has relieved itself of pressure,the valve B can be properly loaded or secured and steam again raised,the fusible metal again setting so as to hold the valve in place readyfor automatic action when again required.

Having thus fully described my invention, what I claim, and desire tosecure by Letters 40 Patent, is-

1. In alow-water safety apparatus for steamboilers, the combination ofthe following elements: an upper tube-flue or crown-sheet having anupwardly-projecting hollow portion, essentiallyasherein described,withthefusiblemetal-containing tube A, of a safety relieving device,substantially as and for the purpose set forth.

2. In alow-water safety apparatus for steamboilers, essentially asherein described, one of the flues or crown-sheets of a boiler having anupw'ardlyproj ecting hollow portion formed by a bonnet, E, and a tube,A, attached thereto and containing a body of fusible metal, incombination with the valve-holding rod a and valve B, essentially asherein described, and for the purpose set forth.

3. In a low-water safety apparatus for steamboilers, essentially asherein described, the combination of the containing-tube A for thefusible metal, valve-holding rod a, valves B and O, the parts beingarranged essentially as herein described, and for the purpose set forth.

4. In alow-water safety apparatus for steamboilers, essentially asherein described, the 6 5 combination of valves B G and their levers B Owith the compensating set screw 0, essentially as herein described, andfor the purpose set forth.

5. Inalow-water safety apparatus for steam- 7o boilers, essentially asherein described, the valve B, formed with a valve portion, b, and adisk or piston portion, b", in combination with the valve 0, connectionsI) 0, tube A, containing a body of fusible metal, rod a, and 75 lever B,essentially as herein described, and for the purpose set forth. 7

In testimony whereof witness my hand this 19th day of February, 1884, atthe city of Chicago, State of Illinois.

JAMES S. GRIFFITH.-

In presence of- ROBERT BURNS, CHAS. F. SHOEMAKER.

